Retinitis pigmentosa (RP) is thought to be caused by genetic mutations in a variety of genes, many of which regulate the specification, maturation, and function of rod and cone photoreceptor cells during retinal development (e.g., Crx, Nrl, Nr2e3, Pde6a, Prph2, Ush2a, Rho, etc.) (Swaroop et al., 2010; Altschwager et al., 2017; Tsang and Sharma, 2018; Gill et al., 2019). The gene discussed is NRL; the disease is retinitis pigmentosa 1.